Technical Field
The present invention relates to a wireless communication device, a wireless communication method, and a storage medium.
Background Art
In recent years, the reduced power consumption short-range wireless communication standard Bluetooth (registered trademark) low energy (BLE) has become more widely used.
Many wireless communication devices that utilize BLE for wireless communication are battery-powered. Such applications demand reductions in inefficient power consumption.
One method for reducing the power consumption associated with wireless communications is to perform the wireless communications intermittently. In this case, the longer the idle period (the period of time during intermittent communication during which no connection is made), the greater the extent to which power consumption can be reduced.
However, during these idle periods, clock signals cannot be synchronized between the wireless communication devices. As a result, the longer the idle period becomes, the greater the difference in the clock signals (the clock error) between the wireless communication devices becomes.
Each wireless communication device keeps track of the timing for communications in accordance with the local clock signal. Therefore, as the clock error between the wireless communication devices increases, the timings at which communication takes place after the idle period become increasingly desynchronized. In this case, the frequency of communications or the scanning time on the receiving side must be increased in order to communicate reliably. This increases the length of the period of time during which the wireless communication devices are actively operating, thereby increasing power consumption.
To solve this problem, there are methods that allow each wireless communication device to calculate the time difference between a local reference timer and a timer on another wireless communication device (the communication partner).
In Japanese Patent Application Laid-Open Publication No. 2014-115794, for example, a master node and a slave node each get the send times or the receive times for communication packets and then calculate the differences between those times. These time differences can be used to correct the clock error.
In the above document, the time differences are only calculated when communication packets are sent or received. As a result, even if the clock error is corrected using a given time difference, the clock error between the wireless communication devices can only be corrected for the time at which the corresponding communication packet was sent or received.
Therefore, during the idle period the clock error between the wireless communication devices cannot be corrected, and that clock error between the wireless communication devices continues to increase as time elapses. As described above, in this case the timings at which communication occurs after the idle period become increasingly desynchronized. This makes it necessary to increase the length of the period of time during which the wireless communication devices are actively operating, thereby increasing power consumption.